Methods for suppressing isomerization of olefin metathesis products

ABSTRACT

A method for suppressing isomerization of an olefin metathesis product produced in a metathesis reaction includes adding an isomerization suppression agent to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst. The isomerization suppression agent is phosphorous acid, a phosphorous acid ester, phosphinic acid, a phosphinic acid ester or combinations thereof. Methods of refining natural oils are described.

FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

This invention was made with government support under Contract No.DE-EE0002872 awarded by Department of Energy. The government has certainrights in the invention.

TECHNICAL FIELD

The present teachings relate generally to methods for suppressing theisomerization of olefins—particularly olefins produced in metathesisreactions.

BACKGROUND

The olefin metathesis reaction is a highly versatile and powerfultechnique for the synthetic preparation of alkenes. Transition metalcarbene complexes—particularly those incorporating ruthenium—are popularcatalysts for metathesis. However, the yield of certain desiredmetathesis products can be significantly reduced by double bondisomerization. This is typically the result of residual metathesiscatalyst and/or its byproducts being present in the reaction mixture.This problem becomes particularly acute if the metathesis mixture isheated and/or distilled in the presence of residual catalyst.

In view of this problem, it is oftentimes necessary to remove residualmetathesis catalyst from an olefinic metathesis product (or otherwisepassivate the residual catalyst) prior to subjecting the olefinicmetathesis product to further chemical reactions and/or processing. Oneapproach, as described in U.S. Pat. No. 6,215,019 B1, has been to addtris(hydroxymethyl)phosphine (THMP) to the reaction mixture as anisomerization inhibitor. Unfortunately, the commercial availability andpricing of THMP are not viable on an industrial scale. Moreover,although THMP can be prepared from precursor salts, such astetrakis(hydroxymethyl)phosphonium sulfate (THPS) ortetrakis(hydroxymethyl)phosphonium chloride (TKC), the conversioninvolves generation of formaldehyde—a known human carcinogen—as abyproduct. In addition, if pH is not strictly controlled during theformation of THMP (e.g., if conditions become too basic), explosivehydrogen gas has been known to form.

An isomerization suppression agent that efficiently passivates residualmetathesis catalyst present in admixture with olefinic metathesisproduct, and which is readily available on a commercial scale but doesnot produce carcinogenic by-products and/or involve the formation ofexplosive hydrogen gas is needed.

SUMMARY

The scope of the present invention is defined solely by the appendedclaims, and is not affected to any degree by the statements within thissummary.

By way of introduction, a first method for suppressing isomerization ofan olefin metathesis product produced in a metathesis reaction includesadding an isomerization suppression agent to a mixture that includes theolefin metathesis product and residual metathesis catalyst from themetathesis reaction under conditions that are sufficient to passivate atleast a portion of the residual metathesis catalyst. The isomerizationsuppression agent is phosphorous acid, phosphinic acid or a combinationthereof.

A second method for suppressing isomerization of an olefin metathesisproduct produced in a metathesis reaction includes: (a) adding anisomerization suppression agent to a mixture that includes the olefinmetathesis product and residual metathesis catalyst from the metathesisreaction under conditions that are sufficient to passivate at least aportion of the residual metathesis catalyst; (b) washing the mixturewith a polar solvent; and (c) separating a phase that includes amajority of the isomerization suppression agent from a phase thatincludes a majority of the olefin metathesis product. The isomerizationsuppression agent is phosphorous acid, phosphinic acid or a combinationthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph showing the effect of phosphorous acid residencetime on degree of isomerization of olefin metathesis products derivedfrom palm oil and soybean oil.

FIG. 2 is a process flow diagram depicting a representative scheme forisomerization suppression in an olefin metathesis product and shows anoptional extraction, separation, and transesterification.

DETAILED DESCRIPTION

A low-cost, effective methodology for suppressing the isomerization ofolefin metathesis products—which is suitable for application on alarge-scale, does not involve the generation of carcinogenic byproducts,such as formaldehyde, and is not susceptible to the generation ofexplosive gas, such as hydrogen—has been discovered and is describedherein. In some embodiments, the inventive methodology facilitatespreservation of the original location of a carbon-carbon double bondcreated during a metathesis reaction, thereby facilitating subsequentprocessing of metathesized product and preserving product integrity.Surprisingly and unexpectedly, in some embodiments, the inventivemethodology utilizes an acid as an isomerization suppression agent—insome embodiments, phosphorous acid (H₃PO₃, aka “phosphonic acid”),phosphinic acid (H₃PO₂, aka “hypophosphorous acid) or a combinationthereof—in spite of the conventional wisdom that has traditionallyregarded acids as being promoters and/or catalysts of olefinisomerization.

DEFINITIONS

Throughout this description and in the appended claims, the followingdefinitions are to be understood:

The term “olefin” refers to a hydrocarbon compound containing at leastone carbon-carbon double bond. As used herein, the term “olefin”encompasses hydrocarbons having more than one carbon-carbon double bond(e.g., di-olefins, tri-olefins, etc.). In some embodiments, the term“olefin” refers to a group of carbon-carbon double bond-containingcompounds with different chain lengths. In some embodiments, the term“olefin” refers to poly-olefins, straight, branched, and/or cyclicolefins.

The term “suppressing” as used in reference to the isomerization of anolefin refers to an inhibitory effect on an olefin's susceptibilitytowards isomerization under a given set of conditions. It is to beunderstood that the term “suppressing” encompasses but does notnecessarily imply 100% suppression (i.e., 0% isomerization).

The term “isomerization” as used in reference to an olefin metathesisproduct refers to the migration of a carbon-carbon double bond in theproduct to another location within the molecule (e.g., from a terminalposition to an internal position and/or from an internal position to aterminal position and/or from a first internal position to a secondinternal position and/or from a first terminal position to a secondterminal position, etc.).

The phrase “olefin metathesis product” refers to any product produced ina metathesis reaction that contains at least one carbon-carbon doublebond. In some embodiments, the “olefin metathesis product” is anunfunctionalized hydrocarbon compound. In some embodiments, the phrase“olefin metathesis product” subsumes the term “olefin.” In someembodiments, the “olefin metathesis product” is functionalized andcontains one or a plurality of additional functional groups in additionto its at least one carbon-carbon double bond.

The term “functionalized” and the phrase “functional group” refer to thepresence in a molecule of one or more heteroatoms at a terminal and/oran internal position, wherein the one or more heteroatoms is an atomother than carbon and hydrogen. In some embodiments, the heteroatomconstitutes one atom of a polyatomic functional group withrepresentative functional groups including but not limited to carboxylicacids, carboxylic esters, ketones, aldehydes, anhydrides, ether groups,cyano groups, nitro groups, sulfur-containing groups,phosphorous-containing groups, amides, imides, N-containingheterocycles, aromatic N-containing heterocycles, salts thereof, and thelike, and combinations thereof.

The phrase “metathesis reaction” refers to a chemical reaction involvinga single type of olefin or a plurality of different types of olefin,which is conducted in the presence of a metathesis catalyst, and whichresults in the formation of at least one new olefin product. The phrase“metathesis reaction” encompasses self-metathesis, cross-metathesis (akaco-metathesis; CM), ring-opening metathesis (ROM), ring-openingmetathesis polymerizations (ROMP), ring-closing metathesis (RCM),acyclic diene metathesis (ADMET), and the like, and combinationsthereof. In some embodiments, the phrase “metathesis reaction” refers toa chemical reaction involving a natural oil feedstock.

The phrases “natural oil,” “natural oil feedstock,” and the like referto oils derived from plant or animal sources. As used herein, thesephrases encompass natural oil derivatives as well, unless otherwiseindicated.

The term “derivative” as used in reference to a substrate (e.g., a“functionalized derivative” of a carboxylic acid, such as 9-decenoicacid, etc.) refers to compounds and/or mixture of compounds derived fromthe substrate by any one or combination of methods known in the art,including but not limited to saponification, transesterification,esterification, amidification, amination, imide preparation,hydrogenation (partial or full), isomerization, oxidation, reduction,and the like, and combinations thereof.

The phrase “natural oil derivatives” refers to compounds and/or mixtureof compounds derived from a natural oil using any one or combination ofmethods known in the art, including but not limited to saponification,transesterification, esterification, amidification, amination,hydrogenation (partial or full), isomerization, oxidation, reduction,and the like, and combinations thereof.

The phrase “low-molecular-weight olefin” refers to any straight,branched or cyclic olefin in the C₂ to C₃₀ range and/or any combinationof such olefins. The phrase “low-molecular-weight olefin” encompassespolyolefins including but not limited to dienes, trienes, and the like.In some embodiments, the low-molecular-weight olefin is functionalized.

The term “ester” refers to compounds having a general formula R—COO—R′,wherein R and R′ denote any substituted or unsubstituted alkyl or arylgroup. In some embodiments, the term “ester” refers to a group ofcompounds having a general formula as described above, wherein thecompounds have different chain lengths.

The phrase “residual metathesis catalyst” refers to a catalytic materialleft over from a metathesis reaction that is capable of participatingin, catalyzing and/or otherwise promoting or facilitating theisomerization of a carbon-carbon double bond although it may or may notstill be capable of catalyzing a metathesis reaction. As used herein,the phrase “residual metathesis catalyst” encompasses wholly unreactedmetathesis catalyst, partially reacted metathesis catalyst, and allmanner of chemical entities derived from a metathesis catalyst over thecourse of a metathesis reaction, including but not limited to all mannerof active or inactive intermediates (e.g., carbenes, metallocycles,etc.), degradation and/or decomposition products (e.g., metal hydrides,ligand fragments, etc.), metals, metal salts, metal complexes, and thelike, and combinations thereof.

The term “passivate” as used in reference to residual metathesiscatalyst refers to any reduction in the activity of the residualmetathesis catalyst vis-à-vis its ability and/or tendency to catalyzeand/or otherwise participate in (e.g., via a stoichiometric chemicalreaction, sequestration or the like) the isomerization of acarbon-carbon double bond. It is to be understood that the term“passivate” encompasses but does not necessarily imply completedeactivation of residual metathesis catalyst towards isomerization of acarbon-carbon double bond.

The phrase “conditions sufficient to passivate” as used in reference tothe conditions under which an isomerization suppression agent is addedto a mixture comprising olefin metathesis product and residualmetathesis catalyst refers to a variable combination of experimentalparameters, which together result in the passivation of at least aportion of residual metathesis catalyst. The selection of theseindividual parameters lies well within the skill of the ordinary artisanin view of the guiding principles outlined herein, and will varyaccording to the target reduction in degree of isomerization that isbeing sought for a particular application. As used herein, the phrase“conditions sufficient to passivate” encompasses experimental parametersincluding but not limited to concentrations of reagents, the type ofmixing and/or stirring provided (e.g., high-shear, low-intensity, etc.),reaction temperature, residence time, reaction pressure, reactionatmosphere (e.g., exposure to atmosphere vs. an inert gas, etc.), andthe like, and combinations thereof.

The phrase “degree of isomerization” as used in relation to an olefinmetathesis product refers to an amount to which a carbon-carbon doublebond in the olefin metathesis product undergoes migration from itsoriginal position to a subsequent position (e.g., the degree to which aninitially formed olefin metathesis product is converted into one or morenon-identical isomers thereof). In some embodiments, the “degree ofisomerization” refers to the degree to which an initially formedα-olefin metathesis product is converted into one or more internalisomers thereof under a given set of conditions (e.g., the amount ofterminal-to-internal migration). In some embodiments, the “degree ofisomerization” refers to the degree to which an olefin metathesisproduct containing an internal carbon-carbon double bond is convertedinto an α-olefin under a given set of conditions (e.g., the amount ofinternal-to-terminal migration). In some embodiments, the “degree ofisomerization” refers to the degree to which an olefin metathesisproduct containing an internal carbon-carbon double bond is convertedinto one or more additional and non-identical internal isomers thereofunder a given set of conditions (e.g., the amount ofinternal-to-internal migration). In some embodiments, the “degree ofisomerization” refers to the degree to which an initially formedα-olefin metathesis product is converted into a different α-olefin undera given set of conditions (e.g., the amount of terminal-to-terminalmigration). In some embodiments, the “degree of isomerization” refers toany combination of the amount of terminal-to-internal migration, theamount of internal-to-terminal migration, the amount ofinternal-to-internal migration, and/or the amount ofterminal-to-terminal migration.

The term “attached” as used in reference to a solid support and anisomerization suppression agent is to be understood broadly and withoutlimitation to encompass a range of associative-type forces, includingbut not limited to covalent bonds, ionic bonds, physical and/orelectrostatic attractive forces (e.g., hydrogen bonds, Van der Waalsforces, etc.), and the like, and combinations thereof.

By way of general background, as mentioned above, the presence ofresidual metathesis catalyst during heating and/or distillation of anolefin metathesis product can result in the isomerization of acarbon-carbon double bond in the product, such that one or more isomersof the original olefin metathesis product are formed. Such isomerizationis generally undesirable when end-group functionalization within theproduct molecule is the goal. In addition, such isomerization isgenerally undesirable when it leads to a mixture of products and thegoal is a well-defined product in high yield and in high purity. Labileolefins and/or olefins that are not as thermodynamically stable as otherisomers readily accessible through isomerization are particularly—thoughby no means exclusively—susceptible to isomerization (e.g., terminalolefins, vinyl olefins, vinylidene olefins, and the like).

By way of example, although methyl 9-decenoate is an expected product ofthe cross-metathesis between methyl oleate and the α-olefin 1-butene, itis found in practice that some isomerization of the 9-substituted olefinto one or more internal olefins (e.g., migration of the double bond tothe 7- and/or 8-positions) can occur when the cross metathesis productis heated prior to removal and/or pacification of residual metathesiscatalyst. To assess the magnitude of the isomerization, thecross-metathesized material obtained from the cross-metathesis betweenmethyl oleate and 1-butene was subjected to typical oil refiningconditions, such as exposure to high temperatures (e.g., about 250° C.).In the absence of any isomerization suppression agent, the degree ofisomerization of methyl 9-decenoate to internal isomers under typicalconditions was observed to be about 25%. It is to be understood,however, that this degree of isomerization is meant solely to beillustrative and that it can vary depending on the particular substrateand conditions.

However, by adding phosphorous acid and/or phosphinic acid as anisomerization suppression agent—particularly though not exclusively inexcess molar amounts relative to residual metathesis catalyst—thepresent inventors found that the degree of isomerization can be greatlyreduced. Moreover, phosphorous acid and phosphinic acid are bothavailable in commercial quantities and neither is subject to the samecarcinogenicity and explosion concerns that are associated with THMPproduction.

It is to be understood that elements and features of the variousrepresentative embodiments described below may be combined in differentways to produce new embodiments that likewise fall within the scope ofthe present teachings.

By way of general introduction, in some embodiments, a method inaccordance with the present teachings for suppressing isomerization ofan olefin metathesis product produced in a metathesis reaction comprisesadding an isomerization suppression agent to a mixture that comprisesthe olefin metathesis product and residual metathesis catalyst from themetathesis reaction. The isomerization suppression agent is added underconditions sufficient to passivate at least a portion of the residualmetathesis catalyst, and is selected from the group consisting ofphosphorous acid, phosphinic acid, and a combination thereof.

After the isomerization suppression agent has been added to the mixturecomprising the olefin metathesis product and residual metathesiscatalyst, the isomerization suppression agent can be left in the mixtureand carried along, either in whole or in part, in a subsequent chemicalreaction or processing step. Alternatively, the isomerizationsuppression agent can be separated and removed from the mixture, eitherpartially or completely, prior to any subsequent reaction or processingstep.

For embodiments in which it is desirable to separate and/or removeisomerization suppression agent following passivation of residualmetathesis catalyst, a method in accordance with the present teachingscan optionally further comprise washing or extracting the metathesisreaction mixture with a polar solvent. In some embodiments, the polarsolvent is at least partially non-miscible with the mixture, such that aseparation of layers can occur. In some embodiments, at least a portionof the isomerization suppression agent is partitioned into the polarsolvent layer, which can then be separated from the non-miscibleremaining layer and removed. Representative polar solvents for use inaccordance with the present teachings include but are not limited towater, alcohols (e.g., methanol, ethanol, etc.), ethylene glycol,glycerol, DMF, multifunctional polar compounds including but not limitedto polyethylene glycols and/or glymes, and the like, and combinationsthereof. In some embodiments, the mixture is extracted with water.

In addition to or as an alternative to washing the mixture with a polarsolvent to remove isomerization suppression agent, a method inaccordance with the present teachings can optionally further compriseremoving at least a portion of the isomerization suppression agent byadsorbing it onto an adsorbent, which optionally can then be physicallyseparated from the mixture (e.g., via filtration or the like). In someembodiments, the adsorbent is polar. Representative adsorbents for usein accordance with the present teachings include but are not limited tocarbon, silica, silica-alumina, alumina, clay, magnesium silicates(e.g., Magnesols), the synthetic silica adsorbent sold under thetradename TRISYL by W. R. Grace & Co., diatomaceous earth, and the like,and combinations thereof.

In some embodiments, the olefin metathesis product comprises at leastone terminal double bond and, in some embodiments, the isomerizationcomprises conversion of the terminal double bond to an internal doublebond. In some embodiments, the olefin metathesis product comprises atleast one internal double bond and, in some embodiments, theisomerization comprises conversion of the internal double bond to adifferent internal double bond (i.e., an internal double bond betweentwo carbon atoms at least one of which was not part of the originalinternal double bond). In some embodiments, the olefin metathesisproduct comprises at least one internal double bond and, in someembodiments, the isomerization comprises conversion of the internaldouble bond to a terminal double bond. In some embodiments, thesuppressing of the isomerization comprises an observed degree ofisomerization that is less than about 5%, in some embodiments less thanabout 4%, in some embodiments less than about 3%, in some embodimentsless than about 2%, in some embodiments less than about 1%, in someembodiments less than about 0.9%, in some embodiments less than about0.8%, in some embodiments less than about 0.7%, in some embodiments lessthan about 0.6%, in some embodiments less than about 0.5%, in someembodiments less than about 0.4%, in some embodiments less than about0.3%, in some embodiments less than about 0.2%, and in some embodimentsless than about 0.1%.

In some embodiments, the olefin metathesis product isα,ω-di-functionalized. In some embodiments, the olefin metathesisproduct comprises a carboxylic acid moiety. In some embodiments, theolefin metathesis product comprises a terminal olefin and a carboxylicacid moiety. In some embodiments, the olefin metathesis productcomprises an internal olefin and a carboxylic acid moiety. In someembodiments, the olefin metathesis product comprises a carboxylic estermoiety. In some embodiments, the olefin metathesis product comprises aterminal olefin and a carboxylic ester moiety. In some embodiments, theolefin metathesis product comprises an internal olefin and a carboxylicester moiety. In some embodiments, the olefin metathesis product isselected from the group consisting of 9-decenoic acid, an ester of9-decenoic acid, 9-undecenoic acid, an ester of 9-undecenoic acid,9-dodecenoic acid, an ester of 9-dodecenoic acid, 1-decene, 2-dodecene,3-dodecene, and combinations thereof. In some embodiments, the esters of9-decenoic acid, 9-undecenoic acid, and 9-dodecenoic acid are alkylesters, and, in some embodiments, methyl esters (e.g., methyl9-decenoate, methyl 9-undecenoate, methyl 9-dodecenoate, etc.).

In some embodiments, the olefin metathesis product is derived from anatural oil reactant. In some embodiments, the metathesis reaction thatproduced the olefin metathesis product comprises self-metathesis of anatural oil and/or a derivative thereof. In some embodiments, themetathesis reaction that produced the olefin metathesis productcomprises cross-metathesis between a natural oil and/or a derivativethereof and a low molecular weight olefin.

Representative examples of natural oils for use in accordance with thepresent teachings include but are not limited to vegetable oils, algaloils, animal fats, tall oils (e.g., by-products of wood pulpmanufacture), derivatives of these oils, and the like, and combinationsthereof. Representative examples of vegetable oils for use in accordancewith the present teachings include but are not limited to canola oil,rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil, palmoil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil,linseed oil, palm kernel oil, tung oil, jatropha oil, mustard oil,pennycress oil, camelina oil, hemp oil, castor oil, and the like, andcombinations thereof. Representative examples of animal fats for use inaccordance with the present teachings include but are not limited tolard, tallow, poultry fat, yellow grease, brown grease, fish oil, andthe like, and combinations thereof. In some embodiments, the natural oilmay be refined, bleached, and/or deodorized.

Representative examples of natural oil derivatives for use in accordancewith the present teachings include but are not limited to gums,phospholipids, soapstock, acidulated soapstock, distillate or distillatesludge, fatty acids, fatty acid alkyl esters (e.g., non-limitingexamples such as 2-ethylhexyl ester, etc.), hydroxy-substitutedvariations thereof, and the like, and combinations thereof. In someembodiments, the natural oil derivative is a fatty acid methyl ester(FAME) derived from the glyceride of the natural oil.

In some embodiments, the low-molecular-weight olefin is an “α-olefin”(aka “terminal olefin”) in which the unsaturated carbon-carbon bond ispresent at one end of the compound. In some embodiments, thelow-molecular-weight olefin is an internal olefin. In some embodiments,the low-molecular-weight olefin is functionalized. In some embodiments,the low-molecular weight olefin is a C₂-C₃₀ olefin. In some embodiments,the low-molecular weight olefin is a C₂-C₃₀ α-olefin. In someembodiments, the low-molecular weight olefin is a C₂-C₂₅ olefin. In someembodiments, the low-molecular weight olefin is a C₂-C₂₅ α-olefin. Insome embodiments, the low-molecular weight olefin is a C₂-C₂₀ olefin. Insome embodiments, the low-molecular weight olefin is a C₂-C₂₀ α-olefin.In some embodiments, the low-molecular weight olefin is a C₂-C₁₅ olefin.In some embodiments, the low-molecular weight olefin is a C₂-C₁₅α-olefin. In some embodiments, the low-molecular weight olefin is aC₂-C₁₀ olefin. In some embodiments, the low-molecular weight olefin is aC₂-C₁₀ α-olefin. In some embodiments, the low-molecular weight olefin isa C₂-C₈ olefin. In some embodiments, the low-molecular weight olefin isa C₂-C₈ α-olefin. In some embodiments, the low-molecular weight olefinis a C₂-C₆ olefin. In some embodiments, the low-molecular weight olefinis a C₂-C₆ α-olefin. Representative low-molecular-weight olefins in theC₂ to C₆ range include but are not limited to ethylene, propylene,1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 3-pentene,2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, cyclopentene,1-hexene, 2-hexene, 3-hexene, 4-hexene, 2-methyl-1-pentene,3-methyl-1-pentene, 4-methyl-1-pentene, 2-methyl-2-pentene,3-methyl-2-pentene, 4-methyl-2-pentene, 2-methyl-3-pentene, 1-hexene,2-hexene, 3-hexene, cyclohexene, and the like, and combinations thereof.In some embodiments, the low-molecular-weight olefin is an α-olefinselected from the group consisting of styrene, vinyl cyclohexane, and acombination thereof. In some embodiments, the low-molecular weightolefin is a mixture of linear and/or branched olefins in the C₄-C₁₀range. In some embodiments, the low-molecular weight olefin is a mixtureof linear and/or branched C₄ olefins (e.g., combinations of 1-butene,2-butene, and/or iso-butene). In some embodiments, the low-molecularweight olefin is a mixture of linear and/or branched olefins in thehigher C₁₁-C₁₄ range.

In some embodiments, the olefin metathesis product comprises at leastone internal double bond, which in some embodiments is cis and in someembodiments is trans. In some embodiments, the olefin metathesis productcomprises at least one terminal double bond and at least one internaldouble bond. In some embodiments, the olefin metathesis productcomprises at least one terminal double bond and/or at least one internaldouble bond, and at least one additional functional group. In someembodiments, the at least one additional functional group is selectedfrom the group consisting of carboxylic acids, carboxylic esters,mono-acylglycerides (MAGs), di-acylglycerides (DAGs), tri-acylglycerides(TAGs), and combinations thereof. In some embodiments, the olefinmetathesis product is produced in a self-metathesis reaction. In someembodiments, the olefin metathesis product is produced in across-metathesis reaction. In some embodiments, the olefin metathesisproduct is a downstream derivative of a self-metathesis orcross-metathesis product (including but not limited to, for example,transesterification products, hydrolysis products, and the like, andcombinations thereof). In some embodiments, the olefin metathesisproduct is produced in a metathesis reaction involving one or morepreviously formed olefin metathesis products (e.g., the production of9-ODDAME from the cross-metathesis of 9-DAME and 9-DDAME—one or both ofwhich is itself a product of a metathesis reaction).

In some embodiments, the metathesis reaction that produced the olefinmetathesis product comprises the reaction of two triglycerides presentin a natural feedstock in the presence of a metathesis catalyst(self-metathesis), wherein each triglyceride comprises at least onecarbon-carbon double bond, thereby forming a new mixture of olefins andesters that in some embodiments comprises a triglyceride dimer. In someembodiments, the triglyceride dimer comprises more than onecarbon-carbon double bond, such that higher oligomers also can form. Insome embodiments, the metathesis reaction that produced the olefinmetathesis product comprises the reaction of an olefin (e.g., alow-molecular weight olefin) and a triglyceride in a natural feedstockthat comprises at least one carbon-carbon double bond, thereby formingnew olefinic molecules as well as new ester molecules(cross-metathesis).

In some embodiments, the residual metathesis catalyst comprises atransition metal. In some embodiments, the residual metathesis catalystcomprises ruthenium. In some embodiments, the residual metathesiscatalyst comprises rhenium. In some embodiments, the residual metathesiscatalyst comprises tantalum. In some embodiments, the residualmetathesis catalyst comprises nickel. In some embodiments, the residualmetathesis catalyst comprises tungsten. In some embodiments, theresidual metathesis catalyst comprises molybdenum.

In some embodiments, the residual metathesis catalyst comprises aruthenium carbene complex and/or an entity derived from such a complex.In some embodiments, the residual metathesis catalyst comprises amaterial selected from the group consisting of a ruthenium vinylidenecomplex, a ruthenium alkylidene complex, a ruthenium methylidenecomplex, a ruthenium benzylidene complex, and combinations thereof,and/or an entity derived from any such complex or combination of suchcomplexes. In some embodiments, the residual metathesis catalystcomprises a ruthenium carbene complex comprising at least onetricyclohexylphosphine ligand and/or an entity derived from such acomplex. In some embodiments, the residual metathesis catalyst comprisesa ruthenium carbene complex comprising at least twotricyclohexylphosphine ligands [e.g., (PCy₃)₂Cl₂Ru═CH—CH═C(CH₃)₂, etc.]and/or an entity derived from such a complex. In some embodiments, theresidual metathesis catalyst comprises a ruthenium carbene complexcomprising at least one imidazolidine ligand and/or an entity derivedfrom such a complex. In some embodiments, the residual metathesiscatalyst comprises a ruthenium carbene complex comprising anisopropyloxy group attached to a benzene ring and/or an entity derivedfrom such a complex.

In some embodiments, the residual metathesis catalyst comprises aGrubbs-type olefin metathesis catalyst and/or an entity derivedtherefrom. In some embodiments, the residual metathesis catalystcomprises a first-generation Grubbs-type olefin metathesis catalystand/or an entity derived therefrom. In some embodiments, the residualmetathesis catalyst comprises a second-generation Grubbs-type olefinmetathesis catalyst and/or an entity derived therefrom. In someembodiments, the residual metathesis catalyst comprises afirst-generation Hoveda-Grubbs-type olefin metathesis catalyst and/or anentity derived therefrom. In some embodiments, the residual metathesiscatalyst comprises a second-generation Hoveda-Grubbs-type olefinmetathesis catalyst and/or an entity derived therefrom. In someembodiments, the residual metathesis catalyst comprises one or aplurality of the ruthenium carbene metathesis catalysts sold by Materia,Inc. of Pasadena, Calif. and/or one or more entities derived from suchcatalysts. Representative metathesis catalysts from Materia, Inc. foruse in accordance with the present teachings include but are not limitedto those sold under the following product numbers as well ascombinations thereof: product no. C823 (CAS no. 172222-30-9), productno. C848 (CAS no. 246047-72-3), product no. C601 (CAS no. 203714-71-0),product no. C627 (CAS no. 301224-40-8), product no. C571 (CAS no.927429-61-6), product no. C598 (CAS no. 802912-44-3), product no. C793(CAS no. 927429-60-5), product no. C801 (CAS no. 194659-03-9), productno. C827 (CAS no. 253688-91-4), product no. C884 (CAS no. 900169-53-1),product no. C833 (CAS no. 1020085-61-3), product no. C859 (CAS no.832146-68-6), product no. C711 (CAS no. 635679-24-2), product no. C933(CAS no. 373640-75-6).

In some embodiments, the isomerization suppression agent comprisesphosphorous acid. Since phosphorous acid has a melting point of 73.6° C.and is typically a solid at room temperature, in some embodiments inaccordance with the present teachings, neat phosphorous acid (i.e., insubstantially solid form) is added to the mixture that comprises theolefin metathesis product and residual metathesis catalyst.

In some embodiments, the isomerization suppression agent comprises asolution of phosphorous acid. In some embodiments, the solution isaqueous. It is to be understood that the concentration of phosphorousacid is not restricted, and that all manner of concentrations arecontemplated for use in accordance with the present teachings. In someembodiments, the isomerization suppression agent comprises an aqueoussolution of phosphorous acid in a concentration of between about 1 wt %and about 70 wt %. In some embodiments, the isomerization suppressionagent comprises an aqueous solution of phosphorous acid in aconcentration of between about 5 wt % and about 50 wt %. In someembodiments, the isomerization suppression agent comprises an aqueoussolution of phosphorous acid in a concentration of between about 7 wt %and about 15 wt %. In some embodiments, the isomerization suppressionagent comprises an aqueous solution of phosphorous acid in aconcentration of about 10 wt %.

In alternative embodiments, the isomerization suppression agentcomprises an organic rather than aqueous solution of phosphorous acid.Representative organic solvents for use in forming organic solutions ofphosphorous acid include but are not limited to alcohols (e.g.,methanol, ethanol, etc.), acetonitrile, ethylene glycol, glycerol,glymes, polyethylene glycols, and the like, and combinations thereof.

In some embodiments, the isomerization suppression agent comprisesphosphorous acid and is attached to a solid support (e.g., silica gel).In some embodiments, the solid support comprises one or more polarfunctional groups. Representative solid supports for use in accordancewith the present teachings include but are not limited to carbon,silica, silica-alumina, alumina, clay, magnesium silicates (e.g.,Magnesols), the synthetic silica adsorbent sold under the tradenameTRISYL by W. R. Grace & Co., diatomaceous earth, and the like, andcombinations thereof.

In some embodiments, the isomerization suppression agent comprisesphosphinic acid. However, since phosphinic acid and its salts aredesignated as a List I precursor chemical by the United States DrugEnforcement Administration (DEA)—thereby subjecting its handlers withinthe United States to stringent regulatory controls pursuant to theControlled Substances Act and 21 CFR §§1309 and 1310—in someembodiments, the isomerization suppression agent comprises phosphorousacid rather than phosphinic acid.

For embodiments in which the isomerization suppression agent comprisesphosphinic acid, the phosphinic acid can be added to a mixture inaccordance with the present teachings in neat (i.e., in substantiallysolid form) and/or solution form. Since phosphinic acid has a meltingpoint of 26.5° C., it may or may not be a solid at room temperature.

In some embodiments, the isomerization suppression agent comprises asolution of phosphinic acid. In some embodiments, the solution isaqueous. It is to be understood that the concentration of phosphinicacid is not restricted, and that all manner of concentrations arecontemplated for use in accordance with the present teachings.Typically, phosphinic acid is commercially available as a 50 wt %aqueous solution. In some embodiments, the isomerization suppressionagent comprises an aqueous solution of phosphinic acid in aconcentration of between about 1 wt % and about 50 wt %. In someembodiments, the isomerization suppression agent comprises an aqueoussolution of phosphinic acid in a concentration of about 50 wt %. Inalternative embodiments, the isomerization suppression agent comprisesan organic rather than aqueous solution of phosphinic acid.Representative organic solvents for use in forming organic solutions ofphosphinic acid include but are not limited to alcohols (e.g., methanol,ethanol, etc.), acetonitrile, ethylene glycol, glycerol, glymes,polyethylene glycols, and the like, and combinations thereof.

In some embodiments, the isomerization suppression agent comprisesphosphinic acid and is attached to a solid support (e.g., silica gel).In some embodiments, the solid support comprises one or more polarfunctional groups. Representative solid supports for use in accordancewith the present teachings include but are not limited to carbon,silica, silica-alumina, alumina, clay, magnesium silicates (e.g.,Magnesols), the synthetic silica adsorbent sold under the tradenameTRISYL by W. R. Grace & Co., diatomaceous earth, and the like, andcombinations thereof.

In some embodiments, the isomerization suppression agent is added to amixture in accordance with the present teachings in a molar excessrelative to the residual metathesis catalyst. In some embodiments, themolar excess is at least about 2 to 1. In some embodiments, the molarexcess is at least about 3 to 1. In some embodiments, the molar excessis at least about 4 to 1. In some embodiments, the molar excess is atleast about 5 to 1. In some embodiments, the molar excess is at leastabout 10 to 1. In some embodiments, the molar excess is at least about15 to 1. In some embodiments, the molar excess is at least about 20to 1. In some embodiments, the molar excess is at least about 25 to 1.In some embodiments, the molar excess is at least about 30 to 1. In someembodiments, the molar excess is at least about 35 to 1. In someembodiments, the molar excess is at least about 40 to 1. In someembodiments, the molar excess is at least about 45 to 1. In someembodiments, the molar excess is at least about 50 to 1. In someembodiments, the molar excess is at least about 55 to 1. In someembodiments, the molar excess is at least about 60 to 1. In someembodiments, the molar excess is at least about 65 to 1. In someembodiments, the molar excess is at least about 70 to 1. In someembodiments, the molar excess is at least about 75 to 1. In someembodiments, the molar excess is at least about 80 to 1. In someembodiments, the molar excess is at least about 85 to 1. In someembodiments, the molar excess is at least about 90 to 1. In someembodiments, the molar excess is at least about 95 to 1. In someembodiments, the molar excess is at least about 100 to 1.

In some embodiments, the conditions under which an isomerizationsuppression agent in accordance with the present teachings is added to amixture that comprises an olefin metathesis product and residualmetathesis catalyst comprise mixing. In some embodiments, the mixingcomprises high shear mixing (e.g., mixing of a type sufficient todisperse and/or transport at least a portion of a first phase and/orchemical species into a second phase with which the first phase and/or achemical species would normally be at least partly immiscible).

In some embodiments, the conditions under which an isomerizationsuppression agent in accordance with the present teachings is added to amixture that comprises an olefin metathesis product and residualmetathesis catalyst comprise heating. The present teachings are in noway restricted to any particular heating temperature or range oftemperatures. However, for purposes of illustration, in someembodiments, the conditions under which an isomerization suppressionagent in accordance with the present teachings is added to a mixturethat comprises an olefin metathesis product and residual metathesiscatalyst comprise a heating temperature of about 40° C. or higher. Insome embodiments, the heating comprises a temperature of about 50° C. orhigher. In some embodiments, the heating comprises a temperature ofabout 60° C. or higher. In some embodiments, the heating comprises atemperature of about 70° C. or higher. In some embodiments, the heatingcomprises a temperature of about 80° C. or higher. In some embodiments,the heating comprises a temperature of about 90° C. or higher.

As shown by the bar graph in FIG. 1, a residence time of only about 1minute for olefin metathesis products derived from soybean oil resultedin a low degree of isomerization of only about 2.2%. Moreover, aresidence time of only about 5 minutes for olefin metathesis productsderived from palm oil resulted in even lower degrees of isomerizationwell below 1%. In some embodiments, the molar excess of phosphorous acidand/or phosphinic acid (relative to catalyst) appear to affect theresidence time required to achieve desired degrees of isomerization withhigher molar excesses generally corresponding to shorter residence timesto achieve comparable degrees of suppression.

The present teachings are in no way restricted to any particularduration of residence time. However, for purposes of illustration, insome embodiments, the conditions under which an isomerizationsuppression agent in accordance with the present teachings is added to amixture that comprises an olefin metathesis product and residualmetathesis catalyst comprise a residence time of at least about 1minute. In some embodiments, the conditions comprise a residence time ofat least about 2 minutes. In some embodiments, the conditions comprise aresidence time of at least about 3 minutes. In some embodiments, theconditions comprise a residence time of at least about 4 minutes. Insome embodiments, the conditions comprise a residence time of at leastabout 5 minutes. In some embodiments, the conditions comprise aresidence time of at least about 10 minutes. In some embodiments, theconditions comprise a residence time of at least about 15 minutes. Insome embodiments, the conditions comprise a residence time of at leastabout 20 minutes. In some embodiments, the conditions comprise aresidence time of at least about 25 minutes. In some embodiments, theconditions comprise a residence time of at least about 30 minutes. Insome embodiments, the conditions comprise a residence time of at leastabout 35 minutes. In some embodiments, the conditions comprise aresidence time of at least about 40 minutes. In some embodiments, theconditions comprise a residence time of at least about 45 minutes. Insome embodiments, the conditions comprise a residence time of at leastabout 50 minutes. In some embodiments, the conditions comprise aresidence time of at least about 55 minutes. In some embodiments, theconditions comprise a residence time of at least about 60 minutes. Insome embodiments, the conditions comprise a residence time of one ormore hours.

In some embodiments, the conditions under which an isomerizationsuppression agent in accordance with the present teachings is added to amixture that comprises an olefin metathesis product and residualmetathesis catalyst comprise high shear mixing, heating, and/or aresidence time of at least about 2 minutes.

As presently contemplated, the addition of an isomerization suppressionagent to a mixture that comprises an olefin metathesis product andresidual metathesis catalyst in accordance with the present teachingscan be practiced whenever it is desirable to prevent isomerization of anolefin metathesis product—particularly though not exclusivelypotentially labile olefin products, such as terminal olefins—during anysubsequent handling and/or processing including but not limited toheating, distillation, photolytic exposure, exposure to oxidants, andthe like, and combinations thereof.

In some embodiments, methods for suppressing isomerization of an olefinmetathesis product in accordance with the present teachings can be usedin combination with metathesis-based methods for refining natural oilfeedstocks. Representative metathesis-based methods for refining naturaloil feedstocks include but are not limited to those described in UnitedStates Patent Application Publication No. 2011/0113679 A1, assigned tothe assignee of the present invention.

By way of non-limiting example, in reference to FIG. 1 of United StatesPatent Application Publication No. 2011/0113679 A1, methods forsuppressing isomerization of an olefin metathesis product in accordancewith the present teachings can be implemented prior to introducing themetathesized product 22 to the separation unit 30 (e.g., a distillationcolumn) and/or at one or more additional stages in the process. By wayof further non-limiting example, in reference to FIG. 2 of United StatesPatent Application Publication No. 2011/0113679 A1, methods forsuppressing isomerization of an olefin metathesis product in accordancewith the present teachings can be implemented prior to introducing themetathesized product 122 to the separation unit 130 and/or thehydrogenation unit 125 and/or at one or more additional stages in theprocess.

In some embodiments, as shown in FIG. 2, methods for suppressingisomerization of an olefin metathesis product in accordance with thepresent teachings further comprise a polar solvent wash—in other words,extracting the mixture to which an isomerization suppression agent hasbeen added with a polar solvent (e.g., water). In some embodiments, themetathesis mixture (e.g., a neat mixture that comprises, in someembodiments, natural oil, residual metathesis catalyst, olefinmetathesis product and, optionally, low-molecular-weight olefin) issubstantially immiscible with the polar solvent, such that two layersare formed. For the sake of convenience, these immiscible layers aredescribed herein as being “aqueous” and “organic” although, in someembodiments, the so-called aqueous layer may be comprised of a polarsolvent other than or in addition to water. In some embodiments, thepolar solvent extraction can serve to remove at least a portion of theisomerization suppression agent. In some embodiments, the extractingcomprises high shear mixing although such mixing, in some embodiments,may contribute to undesirable emulsion formation. In some embodiments,the extracting comprises low-intensity mixing (e.g., stirring that isnot high shear). The present teachings are in no way restricted to anyparticular type or duration of mixing. However, for purposes ofillustration, in some embodiments, the extracting comprises mixing thepolar solvent and the mixture together for at least about 1 minute. Insome embodiments, the mixture and the polar solvent are mixed togetherfor at least about 2 minutes, in some embodiments for at least about 5minutes, in some embodiments for at least about 10 minutes, in someembodiments for at least about 15 minutes, in some embodiments for atleast about 20 minutes, in some embodiments for at least about 25minutes, in some embodiments for at least about 30 minutes, in someembodiments for at least about 35 minutes, in some embodiments for atleast about 40 minutes, in some embodiments for at least about 45minutes, in some embodiments for at least about 50 minutes, in someembodiments for at least about 55 minutes, and in some embodiments forat least about 60 minutes.

The present teachings are in no way restricted to any particular amountof polar solvent added to the mixture for the extracting. However, forpurposes of illustration, in some embodiments, the amount by weight ofpolar solvent (e.g., water) added to the mixture for the extracting ismore than the weight of the mixture. In some embodiments, the amount byweight of polar solvent (e.g., water) added to the mixture for theextracting is less than the weight of the mixture. In some embodiments,the weight ratio of the mixture to the water added to the mixture is atleast about 1:1, in some embodiments at least about 2:1, in someembodiments at least about 3:1, in some embodiments at least about 4:1,in some embodiments at least about 5:1, in some embodiments at leastabout 6:1, in some embodiments at least about 7:1, in some embodimentsat least about 8:1, in some embodiments at least about 9:1, and in someembodiments at least about 10:1.

In some embodiments, methods for suppressing isomerization of an olefinmetathesis product in accordance with the present teachings furthercomprise allowing a settling period following the polar solvent wash topromote phase separation. The present teachings are in no way restrictedto any particular duration of settling period. However, for purposes ofillustration, in some embodiments, the settling period is at least about1 minute. In some embodiments, the settling period is at least about 2minutes. In some embodiments, the settling period is at least about 5minutes. In some embodiments, the settling period is at least about 10minutes. In some embodiments, the settling period is at least about 15minutes.

In some embodiments, as shown in FIG. 2, methods for suppressingisomerization of an olefin metathesis product in accordance with thepresent teachings further comprise separating an organic phase from anaqueous phase. In some embodiments, a majority of the isomerizationsuppression agent is distributed in the aqueous phase. In someembodiments, a majority of the olefin metathesis product is distributedin the organic phase. In some embodiments, a majority of theisomerization suppression agent is distributed in the aqueous phase anda majority of the olefin metathesis product is distributed in theorganic phase.

In some embodiments, it is observed that removing excess isomerizationsuppression agent from a cross-metathesized oil by washing with watercan be accompanied by a loss in the overall efficacy of isomerizationsuppression. While neither desiring to be bound by any particular theorynor intending to limit in any measure the scope of the appended claimsor their equivalents, it is presently believed that the reduction inisomerization suppression sometimes observed after a water wash ismerely an artifact of handling. Moreover, it was found that by usingslightly different experimental conditions, water washing can be used toremove P-acids without significantly increasing isomerization levels ifstronger concentrations of the acids (e.g., >1M) are initially used andif the material obtained from the suppression treatment is handled underan inert atmosphere (e.g., nitrogen).

In some embodiments, as shown in FIG. 2, a method in accordance with thepresent teachings for suppressing isomerization of an olefin metathesisproduct produced in a metathesis reaction comprises (a) adding anisomerization suppression agent to a mixture that comprises the olefinmetathesis product and residual metathesis catalyst from the metathesisreaction under conditions sufficient to passivate at least a portion ofthe residual metathesis catalyst; (b) extracting the mixture with apolar solvent; and (c) separating a phase that includes a majority ofthe isomerization suppression agent from a phase that includes amajority of the olefin metathesis product. The isomerization suppressionagent comprises phosphorous acid, phosphinic acid, or a combinationthereof. In some embodiments, the residual metathesis catalyst comprisesruthenium. In some embodiments, the isomerization suppression agentcomprises phosphorous acid in a concentration of about 10 wt % which, insome embodiments, is added in a molar excess relative to the residualmetathesis catalyst. In some embodiments, the molar excess is at leastabout 20 to 1, in some embodiments at least about 30 to 1, in someembodiments at least about 40 to 1, and in some embodiments at leastabout 50 to 1.

In some embodiments—particularly though not exclusively those involvingmetathesis-based methods for refining natural oil feedstocks—methods forsuppressing isomerization of an olefin metathesis product in accordancewith the present teachings further comprise separating the olefinmetathesis product into a metathesized triacylglyceride (m-TAG) fractionand an olefinic fraction, as shown in FIG. 2. A majority of thetriacylglyceride fraction is comprised by molecules comprising one ormore carbon-carbon double bonds and, optionally, one or more additionalfunctional groups, whereas a majority of the olefinic fraction iscomprised by molecules comprising one or more unsaturated carbon-carbonbonds and no additional functional groups.

In some embodiments—particularly though not exclusively those involvingmetathesis-based methods for refining natural oil feedstocks—methods forsuppressing isomerization of an olefin metathesis product in accordancewith the present teachings further comprise transesterifying thetriacylglyceride fraction to produce one or a plurality oftransesterification products, as shown in FIG. 2. In some embodiments,the transesterification products comprise fatty acid methyl esters(FAMEs). In some embodiments—particularly though not exclusively thoseinvolving metathesis-based methods for refining natural oilfeedstocks—methods for suppressing isomerization of an olefin metathesisproduct in accordance with the present teachings further compriseseparating the transesterification products from a glycerol-containingphase, as shown in FIG. 2.

In some embodiments, methods for suppressing isomerization of an olefinmetathesis product in accordance with the present teachings compriseextracting the mixture to which an isomerization suppression agent hasbeen added with a polar solvent (e.g., water) and separating an organicphase from an aqueous phase as described above. In some embodiments, theresidual metathesis catalyst in the mixture comprises ruthenium. In someembodiments, a majority of the ruthenium is carried into an organicphase and a minority of the ruthenium is distributed in an aqueousphase. In some embodiments, at least about 51% of the ruthenium isextracted into an organic phase. In some embodiments, at least about 60%of the ruthenium is extracted into an organic phase. In someembodiments, at least about 65% of the ruthenium is extracted into anorganic phase. In some embodiments, at least about 70% of the rutheniumis extracted into an organic phase. In some embodiments, at least about75% of the ruthenium is extracted into an organic phase. In someembodiments, at least about 80% of the ruthenium is extracted into anorganic phase. In some embodiments, at least about 85% of the rutheniumis extracted into an organic phase. In some embodiments, at least about90% of the ruthenium is extracted into an organic phase.

In some embodiments—particularly though not exclusively those involvingmetathesis-based methods for refining natural oil feedstocks—methods forsuppressing isomerization of an olefin metathesis product in accordancewith the present teachings further comprise separating the olefinmetathesis product into a triacylglyceride fraction and an olefinicfraction, transesterifying the triacylglyceride fraction to produce oneor a plurality of transesterification products (e.g., FAMEs), andseparating the transesterification products from a glycerol-containingphase, as shown in FIG. 2. In some embodiments, the residual metathesiscatalyst in the mixture comprises ruthenium. In some embodiments, amajority of the ruthenium is distributed between the glycerol-containingphase and the less polar FAME phase.

In some embodiments, a method of refining a natural oil in accordancewith the present teachings comprises: (a) providing a feedstockcomprising a natural oil; (b) reacting the feedstock in the presence ofa metathesis catalyst to form a metathesized product comprising anolefin and an ester; (c) passivating the metathesis catalyst with anagent selected from the group consisting of phosphorous acid, phosphinicacid, and a combination thereof; (d) separating the olefin in themetathesized product from the ester in the metathesized product; and (e)transesterifying the ester in the presence of an alcohol to form atransesterified product and/or hydrogenating the olefin to form a fullyor partially saturated hydrogenated product.

As noted above, the use of THMP as an isomerizationsuppressor—particularly on an industrial scale—is problematic in view ofits commercial availability and pricing, the fact that a carcinogenicbyproduct, formaldehyde, typically accompanies its preparation, and thepotential that exists to generate explosive H₂ gas if conditions becometoo basic. In addition to these drawbacks, the present inventors havefound that when THMP (as opposed to phosphorous acid and/or phosphinicacid) is used for the suppression of olefin isomerization—particularlywhen the amount of residual metathesis catalyst is low (e.g., in someembodiments less than about 1000 ppm, in some embodiments less thanabout 500 ppm, in some embodiments less than about 250 ppm, and in someembodiments less than about 100 ppm)—reclamation of transition metalfrom the residual metathesis catalyst can be complicated by thedistribution of the transition metal (e.g., ruthenium) between multiplephases with no appreciable concentration or convergence of thetransition metal into any one phase. By way of example, when THMP isused as an isomerization suppression agent in a metathesis-based methodfor refining a natural oil feedstock, such as described above, it isfound that ruthenium is broadly distributed between a water wash streamon the one hand and a glycerol-containing phase and transesterificationproducts on the other. In some studies, about 50% of the total rutheniumwas carried into a water wash stream with the remaining Ru beingdistributed between a glycerol-containing phase and thetransesterification products. While neither desiring to be bound by anyparticular theory nor intending to limit in any measure the scope of theappended claims or their equivalents, it is presently observed that thedifficulty in concentrating a majority of the transition metal into aparticular stream when THMP is used as the isomerization suppressionagent arises primarily when the amount of ruthenium to be recovered issmall (e.g., about 1 wt % or less). By contrast, when a large amount ofruthenium is involved (e.g., about 1 wt % or more) and THMP is used asthe isomerization suppression agent, a majority of the ruthenium cansuccessfully be concentrated into an aqueous phase and removed.

In some embodiments, for purposes of simplifying the metal reclamationprocess, it would be desirable if the metal to be reclaimed (e.g., insome embodiments, ruthenium) were concentrated primarily in one phaseand, in some embodiments, if that phase were located downstream in theoverall process. Thus, in some embodiments—particularly though notexclusively those involving metathesis-based methods for refiningnatural oil feedstocks—methods for suppressing isomerization of anolefin metathesis product in accordance with the present teachingsprovide a further advantage with respect to the use of THMP inasmuch asa majority of the ruthenium to be reclaimed can be carried into anorganic phase (e.g., a glycerol-containing phase and/or thetransesterification products phase) and a minority of the ruthenium canbe carried into an aqueous phase (e.g., water wash stream).

In some embodiments, the phosphorous acid concentration and molar excessof phosphorous acid (relative to catalyst) appear to affect the aqueousphase distribution of recovered ruthenium. By way of example, anisomerization suppression agent comprising 10 wt % phosphorous acid usedin a molar excess relative to ruthenium-containing residual metathesiscatalyst of 50 to 1 resulted in about 12 wt % of the ruthenium beingrecovered from the aqueous phase.

The following examples and representative procedures illustrate featuresin accordance with the present teachings, and are provided solely by wayof illustration. They are not intended to limit the scope of theappended claims or their equivalents.

EXAMPLES Materials and Methods

Unless otherwise indicated, all chemicals were used as received andwithout drying. Palm oil was obtained from Wilmar International Limited.Kirkland soybean oil was purchased from retail sources. 1-Octene waspurchased from Sigma Aldrich. C827 ruthenium catalyst was obtained fromMateria, Inc. Phosphorous acid (spec. 622, lot no. 2010-05-14, suppliedneat) and phosphinic acid (spec. 605, lot no. 091006, 50 wt % in water)were obtained from Special Materials Company. Silica gel was DavisilGrade 633 (W. R. Grace & Co. supplied through Sigma Aldrich, pore size60 Å, 200-425 mesh, batch no. 04720TD). Magnesol Polysorb 30/40 wassupplied by Dallas Corporation (SRR 000-60-4).

Unless otherwise specified, all isomerization results were derived froma small scale isomerization (SSI) unit as described below. By way ofillustration, taking the amount of terminal-to-internal migration as arepresentative and non-limiting example, the degree of isomerization canbe calculated by first obtaining the quotient of (i) the amount ofinternal isomers as represented, for example, by the areas under gaschromatograpy (GC) peaks corresponding to these internal isomers to (ii)the total amount of all isomers—both terminal and internal—asrepresented, for example, by the areas under the GC peaks correspondingto these isomers, and then multiplying this quotient by 100. Analogouscalculations can be performed to determine the amount ofinternal-to-terminal migration and/or the amount of internal-to-internalmigrations. Table 1 below summarizes isomerization suppression resultsfrom various P-acids.

Example 1 Small Scale Isomerization (SSI) Studies

Metathesized samples were heated to 250° C. for one hour under nitrogenafter suppression treatment. Duplicates runs were conducted on both thesample to be tested as well as a control sample which had not beentreated. Degree of isomerization was determined by taking the total ofisomers of methyl 9-decenoate divided by the total amount of methyldecenoate multiplied by 100.

The small scale isomerization unit includes a cylindrical aluminum blockhaving several holes (e.g., six to eight) drilled therein. The aluminumblock is placed on a hot plate and heated to the requisite temperature.Small amounts (typically several grams) of metathesis product are placedin glass tubes, which are then fitted with plastic heads providing anopening for a slight positive pressure of nitrogen to be present abovethe mixture. After purging the samples for 30 minutes under nitrogen,the mixtures are heated to 250° C. (with or without stirring) for onehour by placing the glass tubes in the opening of the aluminum block.The resulting triacylglycerides (TAGs) are then transesterified withmethanol and base and the resulting FAMEs are analyzed by GC. In someembodiments, methyl 9-decenoate is measured vis-à-vis the amount of itsinternal isomers (if any).

Example 2 Preparation of a Cross-Metathesized Olefin Product

Octenylized palm oil was prepared as follows. At a 3:1 molar ratio,1-octene (33.33 g) was added to palm oil (50 g), which had beenpre-treated by heating at 200° C. or above for one hour with N₂sparging. As used herein, the mole ratio of cross agent (e.g., 1-octene)to oil relates to the molar ratio of double bond content. In the oil,the double bond content is calculated from the relative ratio of the keyfatty acids present (each with its own olefin content), all of which canbe readily determined by gas chromatography after transesterification.Thus, in this example, a 3:1 mole ratio refers to having a 3:1 ratio ofcross agent double bonds to the total double bonds of the oil. Theresultant material was then heated with stirring to 60° C. with N₂sparging for 30-45 minutes. Once oxygen had been removed, the nitrogenline was pulled up into the headspace. The metathesis catalyst (C827;2.75 mg, approximately 55 ppm loading) was then added. The reaction wasrun for two hours with periodic sampling of the oil to determine theextent of conversion of the reaction.

Example 3 Phosphorous Acid as Isomerization Suppression Agent

To 70 grams of cross-metathesized soybean oil (3:1 octenylized at a 55ppm catalyst loading), a 50-fold molar excess of a 10% phosphorous acidsolution was added. The reaction was run at 90° C. for 15 minutes underN₂ and shear mixing. The material was then transferred under N₂ to alarger round-bottomed flask and equipped with a distillation head. Thecontents were water washed at a 5:1 oil-to-water ratio for 30 minutes(stirring at 90° C.). The stirring was turned off and the water/oillayers were allowed to separate. The water layer was removed via apipette. The unit was then heated to 250° C. for one hour allowing lightcomponents to leave the system. The level of isomerization of thebottoms product was observed to be 0.2%. The samples were also run undersmall scale isomerization (SSI) and were found to have only 0.3%isomerization. The control (an untreated octenolyzed soybean oil) had an11.5% level of isomerization.

Example 4 Phosphinic Acid as Isomerization Suppression Agent

To 30 grams of cross-metathesized palm oil (1:1 octenylized at a loadingof 40 ppm C827 metathesis catalyst was added a 25-fold molar excess ofphosphinic acid (1M solution in water). The resultant material washeated to 80° C. for one hour with stirring under N₂ and then tested ina small scale isomerization (SSI) unit (heating at 250° C. for onehour). The level of isomerization for the phosphinic acid-treated samplewas observed to be 0.6% and 0.3% (duplicate runs). Similar behavior wasobserved with phosphorous acid. As a point of reference, the level ofisomerization observed for a control sample that was not treated withany isomerization suppression agent was 27.2% and 31.8% (duplicateruns).

Example 5 Phosphinic Acid as Isomerization Suppression Agent

To 165 grams of cross-metathesized palm oil (3:1 octenylized at a 55 ppmcatalyst loading), a 100-fold molar excess of a 50% phosphinic acidsolution was added. The reaction was run at 90° C. for 1 hour under N₂.The material was then transferred under N₂ to a larger round-bottomedflask and equipped with a distillation head. The contents were waterwashed with a 2.5% phosphinic water wash (mimic of recycle wash) for 30minutes (stirring at 90° C.). The stirring was turned off and thewater/oil layers were allowed to separate. A second water washcontaining only fresh water was run for 30 minutes. The layers wereallowed to separate and the water layer was removed via pipette. Theunit was then heated to 250° C. for one hour allowing light componentsto leave the system. The level of isomerization was observed to be 0.2%.The control (an untreated octenolyzed palm oil) exhibited 36%isomerization.

Example 6 Phosphorous Acid/Phosphinic Acid as Isomerization SuppressionAgent

To a cross-metathesized vegetable oil having been reacted with a Grubbstype catalyst and an α-olefin (e.g., 1-octene) is added a mixture ofphosphorous acid and phosphinic acid such that the relative mole ratioof acid to contained metathesis catalyst is 50:1. The mixture is heatedto 80-90° C. for one hour whereupon the resultant mixture shows littleisomerization (typically less than about 1%) when tested via SSI.

Example 7 Removal of Acids Via Adsorption

To further demonstrate suppression with removal of the acid (viaadsorption), the following experiment was conducted. Octenylized palmoil (30 g, 3:1 with 55 ppm C827 catalyst was treated with 100× molarexcess of 1M phosphinic acid at 80° C. for 60 minutes. The resultantsolution was then treated with 0.1 wt % (based on oil) of MagnesolPolysorb 30/40. The solution was stirred for 30 min at 80° C. and thenfiltered. The filtered solution was found to have a degree ofisomerization of 0.6% and 0.3% (duplicate runs) as compared to anunsuppressed degree of isomerization of 41.2%. To demonstrate that theMagnesol was effective in removing the acid, the Magnesol-treatedsolution was extracted with water, and the pH of the water extract wasobserved to be neutral (pH=7). By comparison, when water washing theacids from the treated oil, a pH in the range of 0-1 was observed.

Example 8 Solid-Support of Isomerization Suppression Agent

To 5 grams of Davison silica was added water (22 grams, enough to give aslurry). Next, 1 gram of 50% phosphinic acid (obtained from SMC) wasadded. The resultant material was concentrated under reduced pressure ona rotary evaporator, and after approximately 30 minutes, a white,free-flowing solid (5.12 grams) was obtained, which was used in the nextreaction.

To 30 grams of a cross-metathesized octenylized palm oil reactionmixture was added 30 mg (0.1 wt %) of the phosphinic acid-silica gelsupported material prepared as described above. The mixture was stirredand heated under N₂ for 30 minutes. The material was then filtered andthe resultant oil solution was subjected to isomerization testing. Thetreated sample showed a maximum degree of isomerization of only 0.1%under SSI testing, in stark contrast to the 39.2% degree ofisomerization that was observed for a cross-metathesis reaction mixturethat was not treated with isomerization suppression agent.

TABLE 1 P-ACID - ISOMERIZATION SUPPRESSION RESULTS OF P-ACIDS MolarIsom. Excess over (dupli- Isom. Acid Catalyst cates) (Control) CommentsPhosphinic 50 4.5, 0.8 30.9 Phosphinic 100 1.5, 2.4 16.3 Phosphinic 1000.5, 0.5 16.8 Phosphinic 25 0.6, 0.3 31.8 Higher with ext. Phosphorous100 0.2, 0.2 22.4 With and without water ext. Phosphorous 50 0.3, 0.337.4 Higher with ext. Phosphorous excess 0.3 7 Supported on Magnesolremoval agent

The entire contents of each of U.S. Pat. No. 6,215,019 B1 and UnitedStates Patent Application Publication No. 2011/0113679 A1 cited aboveare hereby incorporated by reference, except that in the event of anyinconsistent disclosure or definition from the present specification,the disclosure or definition herein shall be deemed to prevail.

The foregoing detailed description and accompanying drawings have beenprovided by way of explanation and illustration, and are not intended tolimit the scope of the appended claims. Many variations in the presentlypreferred embodiments illustrated herein will be apparent to one ofordinary skill in the art, and remain within the scope of the appendedclaims and their equivalents

It is to be understood that the elements and features recited in theappended claims may be combined in different ways to produce new claimsthat likewise fall within the scope of the present invention. Thus,whereas the dependent claims appended below may depend from only asingle independent or dependent claim, it is to be understood that thesedependent claims can, alternatively, be made to depend in thealternative from any preceding claim—whether independent ordependent—and that such new combinations are to be understood as forminga part of the present specification.

1. A method for suppressing isomerization of an olefin metathesisproduct produced in a metathesis reaction, the method comprising: addingan isomerization suppression agent to a mixture that comprises theolefin metathesis product and residual metathesis catalyst from themetathesis reaction under conditions that are sufficient to passivate atleast a portion of the residual metathesis catalyst; wherein theisomerization suppression agent is selected from the group consisting ofphosphorous acid, phosphinic acid, and a combination thereof.
 2. Theinvention of claim 1 wherein the olefin metathesis product comprises aterminal double bond.
 3. The invention of claim 2 wherein theisomerization comprises conversion of the terminal double bond to aninternal double bond.
 4. The invention of claim 1 wherein the olefinmetathesis product comprises an internal double bond.
 5. The inventionof claim 4 wherein the isomerization comprises conversion of theinternal double bond to a different internal double bond.
 6. Theinvention of claim 4 wherein the isomerization comprises conversion ofthe internal double bond to a terminal double bond.
 7. The invention ofclaim 1 wherein the olefin metathesis product is α,ω-di-functionalized.8. The invention of claim 7 wherein the olefin metathesis productcomprises a carboxylic acid moiety or a derivative thereof.
 9. Theinvention of claim 7 wherein the olefin metathesis product comprises acarboxylic ester moiety.
 10. The invention of claim 7 wherein the olefinmetathesis product is selected from the group consisting of 9-decenoicacid, an ester of 9-decenoic acid, 9-undecenoic acid, an ester of9-undecenoic acid, 9-dodecenoic acid, an ester of 9-dodecenoic acid,1-decene, 2-dodecene, 3-dodecene, and combinations thereof.
 11. Theinvention of claim 1 wherein the olefin metathesis product is derivedfrom a natural oil reactant.
 12. The invention of claim 11 wherein thenatural oil is selected from the group consisting of canola oil,rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil, palmoil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil,linseed oil, palm kernel oil, tung oil, jatropha oil, mustard oil,camelina oil, pennycress oil, hemp oil, algal oil, castor oil, lard,tallow, poultry fat, yellow grease, fish oil, tall oils, andcombinations thereof.
 13. The invention of claim 1 wherein themetathesis reaction comprises self-metathesis of a natural oil.
 14. Theinvention of claim 1 wherein the metathesis reaction comprisescross-metathesis between a natural oil and a low molecular weightolefin.
 15. The invention of claim 1 wherein the metathesis reactioncomprises cross-metathesis between a natural oil and a C₂-C₁₄ olefinthat comprises a terminal double bond.
 16. The invention of claim 15wherein the natural oil is selected from the group consisting of canolaoil, rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil,palm oil, peanut oil, safflower oil, sesame oil, soybean oil, sunfloweroil, linseed oil, palm kernel oil, tung oil, jatropha oil, mustard oil,camelina oil, pennycress oil, hemp oil, algal oil, castor oil, lard,tallow, poultry fat, yellow grease, fish oil, tall oils, andcombinations thereof.
 17. The invention of claim 1 wherein the residualmetathesis catalyst comprises a transition metal selected from the groupconsisting of ruthenium, rhenium, tantalum, nickel, tungsten,molybdenum, and combinations thereof.
 18. The invention of claim 1wherein the residual metathesis catalyst comprises ruthenium.
 19. Theinvention of claim 18 wherein the olefin metathesis product is producedin a metathesis reaction catalyzed by a ruthenium carbene complex. 20.The invention of claim 19 wherein the ruthenium carbene complexcomprises a phosphine ligand.
 21. The invention of claim 19 wherein theruthenium carbene complex comprises an imidazolidine ligand.
 22. Theinvention of claim 19 wherein the ruthenium carbene complex comprises anisopropyloxy group attached to a benzene ring.
 23. The invention ofclaim 1 wherein the isomerization suppression agent comprisesphosphorous acid.
 24. The invention of claim 23 wherein neat phosphorousacid is added to the mixture.
 25. The invention of claim 1 wherein theisomerization suppression agent comprises phosphorous acid, which isprovided in an aqueous solution having a concentration of between about1 wt % and about 70 wt %.
 26. The invention of claim 25 wherein theconcentration is between about 5 wt % and about 50 wt %.
 27. Theinvention of claim 25 wherein the concentration is between about 7 wt %and about 15 wt %.
 28. The invention of claim 25 wherein theconcentration is about 10 wt %.
 29. The invention of claim 1 wherein theisomerization suppression agent comprises phosphinic acid.
 30. Theinvention of claim 1 wherein the isomerization suppression agentcomprises phosphinic acid, which is provided in an aqueous solutionhaving a concentration of between about 1 wt % and about 50 wt %. 31.The invention of claim 1 wherein the isomerization suppression agent isadded in a molar excess relative to the residual metathesis catalyst.32. The invention of claim 31 wherein the molar excess is at least about15 to
 1. 33. The invention of claim 31 wherein the molar excess is atleast about 25 to
 1. 34. The invention of claim 32 wherein the molarexcess is at least about 35 to
 1. 35. The invention of claim 31 whereinthe molar excess is at least about 50 to
 1. 36. The invention of claim 1wherein the conditions comprise high shear mixing.
 37. The invention ofclaim 1 wherein the conditions comprise high shear mixing and heating.38. The invention of claim 1 further comprising extracting the mixturewith a polar solvent.
 39. The invention of claim 38 wherein the polarsolvent is selected from the group consisting of water, methanol,ethanol, ethylene glycol, glycerol, DMF, polyethylene glycols, glymes,and combinations thereof.
 40. The invention of claim 38 wherein thepolar solvent comprises water.
 41. The invention of claim 40 furthercomprising separating an organic phase from an aqueous phase.
 42. Theinvention of claim 40 wherein the metathesis reaction comprisescross-metathesis between a natural oil and a C₂-C₁₄ olefin thatcomprises a terminal double bond.
 43. The invention of claim 42 furthercomprising separating an organic phase from an aqueous phase, wherein amajority of the isomerization suppression agent is distributed in theaqueous phase and wherein a majority of the olefin metathesis product isdistributed in the organic phase.
 44. The invention of claim 43 furthercomprising separating the olefin metathesis product into atriacylglyceride fraction and an olefinic fraction.
 45. The invention ofclaim 44 further comprising transesterifying the triacylglyceridefraction to produce one or a plurality of transesterification products.46. The invention of claim 45 further comprising separating thetransesterification products from a glycerol-containing phase.
 47. Theinvention of claim 46 wherein the residual metathesis catalyst comprisesruthenium, and wherein a majority of the ruthenium is distributedbetween the glycerol-containing phase and the transesterificationproducts.
 48. The invention of claim 45 wherein the transesterificationproducts comprise fatty acid methyl esters.
 49. The invention of claim 1wherein the isomerization is reduced to less than about 1% by weight ofthe olefin metathesis product.
 50. The invention of claim 1 wherein theisomerization suppression agent is attached to a solid support.
 51. Theinvention of claim 1 further comprising adsorbing at least a portion ofthe isomerization suppression agent onto an adsorbent.
 52. The inventionof claim 51 further comprising physically separating the adsorbent fromthe mixture.
 53. The invention of claim 51 wherein the adsorbent isselected from the group consisting of carbon, silica, silica-alumina,alumina, clay, magnesium silicates, TRISYL synthetic silica,diatomaceous earth, and the like, and combinations thereof.
 54. A methodfor suppressing isomerization of an olefin metathesis product producedin a metathesis reaction, the method comprising: adding an isomerizationsuppression agent to a mixture that comprises the olefin metathesisproduct and residual metathesis catalyst from the metathesis reactionunder conditions that are sufficient to passivate at least a portion ofthe residual metathesis catalyst; washing the mixture with a polarsolvent; and separating a phase comprising a majority of theisomerization suppression agent from a phase comprising a majority ofthe olefin metathesis product; wherein the isomerization suppressionagent is selected from the group consisting of phosphorous acid,phosphinic acid, and a combination thereof.
 55. The invention of claim54 wherein the phase comprising the majority of the isomerizationsuppression agent further comprises a majority of the polar solvent. 56.The invention of claim 54 wherein the residual metathesis catalystcomprises ruthenium.